Torque damper and damping device equipped with such a torque damper

ABSTRACT

The invention concerns a torque damper arranged between an input element and a rotating output element, and comprising resilient members ( 60 ), with circumferential action, two guide washers associated with one of the elements and axially arranged on either side of a disc associated with the other element, the resilient members ( 60 ) operating between the two guide washers and the disc, by being placed in windows ( 64, 65 ), located opposite provided in the guide washers and in the disc. Said windows ( 64, 65 ) have side edges ( 75, 76 ) on which are adapted to be urged to rest the ends of the resilient members ( 60 ); the windows ( 64, 65 ) of the two guide washers have an external edge ( 77 ) which has a portion offset inward (A), in a zone ( 93 ) not swept by the ends of the resilient members ( 60 ) during the relative travel in rotation, in one direction or the other, of the input and output elements, which portion (A) extends circumferentially in the shape of an arc whose center ( 100 ) is located towards the outside with respect to the rotation axis ( 90 ) of the input and output elements.

STATE OF THE ART

The present invention concerns torsion dampers and damping devicesequipped with such torsion dampers, such as for example the deviceswhich are incorporated in clutch friction members for motor vehicles.

Clutch friction members are known, equipped with a torsion dampingdevice comprising two torsion dampers: a main damper and a predamper.

The main damper has an input element fixed to two guide washers disposedon each side of a disc. The guide washers are connected together bystruts, which fix them to each other. The input element consists, in thecase of an application to a clutch friction member, of a support disc oneach face of which friction linings are fixed, intended to be clampedbetween the thrust and reaction plates of the clutch.

As a variant, the input element can consist of a disc fixed directly tothe vehicle engine flywheel; this can also be one of the guide washerswhich is extended radially and fixed directly to the engine flywheel.

The input element, when it is a case of a friction lining support disc,is pressed against one of the guide washers of the main damper whilstbeing fixed thereto by the struts or, as a variant, by specific rivets.

The struts pass through scallops formed at the external periphery of thedisc; in this case, the angular movement between the disc and guidewashers is limited through the cooperation of the struts with the edgeof the scallops.

As a variant, this limitation is achieved by the fact that the helicalsprings constituting circumferentially acting elastic members, here withhigh stiffness, elastically coupling the guidance washers and the disc,come to have contiguous turns.

The guide washers surround the output element of the damper deviceconsisting in general of an internally fluted hub; the same applies tothe disc of the main damper, which for its part meshes with clearancewith the hub. The main damper is therefore kinematically driven directlyby the input element.

The predamper is located between the disc and one of the guide washersof the main damper, and this radially below the springs of the maindamper.

The predamper is placed kinematically directly upstream of the outputelement and also has two guide washers disposed on each side of a discfixed with respect to rotation to the hub by means of teeth. Elasticmembers, such as helical springs, elastically couple the disc of thepredamper to its associated guide washers. This predamper disc iscrimped to the hub, whose flutes have a different height in order toform a shoulder serving to fix the said disc axially.

In such a device with two dampers, the guide washers of the predamperare connected with respect to rotation to the disc of the main damper.The circumferentially acting springs of the predamper are less stiffthan the circumferentially acting springs of the main damper.

The predamper is adapted to filter the vibrations in the idling range ofthe engine, whilst the main damper is adapted to filter the vibrationsin the normal operating range of the vehicle, referred to as the runningrange, as from the idling range of the engine; the predamper can also beadapted to filter the vibrations in the running range at low enginetorque.

The efficacy of a torsion damping device with regard to thelow-frequency torsional vibrations in the vehicle running range, as fromidling of the engine up to 2500 revolutions per minute, for example,requires a large angular movement between the driving element and thedriven element, for example around 40°, this movement taking placecounter to circumferentially acting elastic members elastically couplingthe guide washers and the disc of the main damper.

Generally, the elastic members are helical springs disposed in windowsformed in the guide washers and the disc, respectively. The threewindows receiving one and the same spring, namely the two windows in theguide washers and the window in the disc, are in line with each other;each of these windows has an internal edge, two lateral or supportedges, and an external edge; as shown schematically in FIGS. 1 and 2,the windows 11 in the disc 1 and the windows 12 and 13 in the guidewashers 2 and 3 respectively have an internal edge 14 and 114 andlateral edges 15, 16 and 115, 116 disposed along the three sides of arectangle, the internal edge 14 or 114 extending along the length of thesaid rectangle; the external edge 17, 117 which faces the internal edge14, 114 is curvilinear in shape with its concavity directed towards theinternal edge 14, 114, in other words towards the axis 90 about whichthe disc 1 and guide washers 2 and 3 rotate in operation. In FIG. 1, thecontours of these three windows have been superimposed in plan view forconvenience of the drawing; in practice, where it is a case notably ofthe windows 12 and 13 in the guide washers 2 and 3, the lateral edges115 and 116 are offset axially with respect to the internal 114 andexternal 117 edges, which form part of a flap 18, 19, as shown in FIG.2; in FIG. 1, the external edge 117 and the internal edge 114 of thewindows in the guide washers have been illustrated by a linerepresenting the projection along the axis 90, in the plane of thefigure, of the generator which guides the helical spring 20 radially; inorder to facilitate reading of the drawing, the window in the disc 11 isin solid lines, the dotted lines designating a window formed in theguide washers.

The helical spring 20 is a conventional spring whose axis 21 isrectilinear; when the spring 20 is placed in the windows 11, 12 and 13,its axis 21 is parallel to the internal edge 14, 114 of the said windowsand its end turns are in abutment on the lateral edges 15, 115 and 16,116 of the said windows. The seating of the said end turns is perfect,and when there is a relative angular movement of the input element andoutput element, that is to way of the disc 1 and the guide washers 2 and3, these end turns remain in contact with the said lateral edges,without any relative movement of the said turns with respect to the saidlateral edges; there is therefore no parasitic friction, at the lateraledges 15, 115 and 16, 116, which might interfere with the calculatedinternal friction of the main damper for adjusting its hysteresis.Unfortunately, the above arrangement has the drawback that, inoperation, whilst the torque transmitted by the springs 20 is still weakor nil, the spring 20 subjected to the action of the centrifugal forcehas a tendency to be progressively, with the speed, pressed against theexternal edge of the windows in the guide washers and/or in the discwhilst at the same time it deforms so that its axis 21, initiallyrectilinear, adopts a curved shape whose concavity is turned towards theinside.

The consequences of this are that, on the one hand, parasitic frictionis introduced into the damper and, on the other hand, the ends of theelastic members leave the support edges of the windows. More precisely,FIGS. 1 and 2 show the most usual embodiment in which the guidance roleof the springs 20 is entrusted entirely to the guide washers 2 and 3;this is because, as can be seen in the figures, the end turns of thesprings 20 in abutment on the lateral edges 115, 116 are centred by theinternal 114 and external 117 edges at their junction with the lateraledges 115, 116 respectively; the flaps 18, 19, and therefore theexternal edge 117, are semi-circular: the external edge 117 is an arc ofa circle centred at 91 which is further towards the outside with respectto the axis 90; consequently, the external edge 17 of the window 11 inthe disc 1 is an arc of a circle centred at 92, further towards theoutside compared with the point 91; the external edge 17 is consequentlyan edge with a clearance with respect to the spring 20; however, theends of the said external edge 17 are practically tangent to the endturn of the spring 20 in the region of its connection to the lateraledges 15 and 16; the internal edge 14 is slightly further towards theinside than the internal edges 114 of the windows 12, 13.

Under the effect of centrifugal force, the spring 20 adopts, initially,with a nil or very small transmitted torque, with the engine rotating ata sufficiently high speed, idling for example, a configuration asexplained above and illustrated by FIG. 3, in which it is pressedagainst the external edge 117 of the windows 12 and 13, its axis 21becoming curved and the internal part of the end turns leaving thelateral support edges of the windows; when the speed increases stillfurther, the phenomenon is accentuated as shown in FIG. 4, the end turnsmoving away from the lateral edges; when the disc 1 is moved withrespect to the guide washers 2 and 3, it is the external edge 17 of itswindows 11 which initially comes into contact with the end turn of thespring 20, as illustrated in FIG. 5 by the arrow F; this end turn moves,with friction, along the external edge of the disc 1 until it finds itsabutment position on the lateral edge 15 of the window 11 in the disc 1,and it is only from the moment when the spring has regained its abutmenton the lateral edges 15 and 116 that the torque is transmitted normally.

Naturally, a similar reasoning can be made when the design is such thatit is the disc which is chosen for guiding the springs instead of theguide washers.

It will be understood that everything which has just been stated isvalid if the structures are reversed, that is to say if the inputelement is fixed to the disc and the output element fixed to the twoguide washers. Likewise, the helical springs could be replaced byelastic members made of elastomeric material such as rubber, orcomposite material, for example bonded to two end dishes.

It will be understood that, the longer the springs 20, the greater thedrawbacks described above. Naturally, in order to avoid this drawback,it is possible to use short springs, but this requires, in order toobtain a large movement, a large number of springs disposed in series,which results in a complex design having regard notably to the largenumber of components, to which there is added the difficulty ofcontrolling the parasitic friction.

There has already been proposed, notably in the document FR-A-2 714 436,a torsion damper disposed between two rotating elements, an inputelement and an output element, and having circumferentially actingelastic members, two guide washers associated with one of the elementsand disposed axially on each side of a disc associated with the otherone of the elements, the circumferentially acting elastic members havingan axis and acting between the two guide washers and the disc whilstbeing placed in windows placed opposite each other and formed in theguide washers and in the disc, the said windows having two lateral edgeson which the ends of the elastic members are adapted to be in abutment,the windows having an external edge, the external edge of the windowsformed in one of the guide washers having a portion offset internally,that is to say radially towards the rotation axis of the input andoutput elements, in an area which is not swept by the ends of theelastic members during the relative rotational movement, in onedirection or the other, of the input and output elements; as providedfor in this document, the offset portion, seen in a plane perpendicularto the axis of the clutch, has a V shape whose apex is directed towardsthe said axis and defines locally an axially oriented portion.

Such an arrangement in general gives satisfaction; however, it mayhappen, in certain cases, that, when the elastic members, under theeffect of centrifugal force, come into contact with this offset portion,they are, on this contact, offset axially because this offset portion ispresent on only one side with respect to the disc: consequently, thecurved shape adopted by the axis of the elastic means is no longer planeand the functioning of the spring is disturbed. Moreover, the T shape ofthe offset portion may prevent even deformation of the elastic meansunder the effect of the centrifugal force.

The object of the present invention is to avoid these drawbacks.

SUMMARY OF THE INVENTION

According to the invention, a torsion damper of the above type ischaracterised by the fact that the windows in the two guide washers havean external edge having an internally offset portion, which extendscircumferentially in the shape of an arc of a circle whose centre issituated towards the outside with respect to the rotation axis of theinput and output elements.

Advantageously, the said external edge is connected to the lateral edgesby connecting portions in the shape of an arc of a circle centred on therotation axis of the input and output elements; between the internallyoffset portion on the one hand and each of the connecting portions onthe other hand, the external edge has clearance portions offset radiallytowards the outside.

Advantageously, the clearance portions are arcs of a circle belonging tothe same circle with the same centre as that which defines theinternally offset portion.

Preferably, the said external edge is the external edge of the windowsformed in the guide washers.

Advantageously, the elastic members are helical springs coiled aroundtheir axis.

The damper according to the invention is well suited to an applicationto a motor vehicle: the input element is intended to be fixed or fixableto the vehicle engine flywheel, the output element being intended to beconnected to the input to the vehicle gearbox.

Another object of the invention is a damping device comprising on theone hand a main damper kinematically acted on directly by the inputelement and on the other hand a predamper placed directly upstream ofthe output element, in which the main damper is a torsion damper asabove.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to give a better understanding of the object of the invention,a description will now be given, by way of example, purely illustrativeand non-limitative, of one embodiment depicted in the accompanyingdrawings.

In these drawings:

FIGS. 1 to 5 are explanatory diagrams relating to the prior art alreadycommented on above;

FIG. 6 is a view in section of a clutch friction disc having a damperaccording to the invention;

FIG. 7 is a partial side view of the disc of FIG. 6, to a smaller scale;

FIG. 8 is a diagram showing a window in plan view according to theinvention.

PREFERRED EXAMPLE EMBODIMENTS

Referring to FIGS. 6 and 8, a main damper 50 can be seen, having aninput element 51 here fixed to guide washers 52, 53 disposed on eachside of a disc 54. The guide washers 52, 53 are connected together bystruts 57 which fix them together. Circumferentially acting elasticmembers 60, here helical springs, elastically couple the disc 54 to theguide washers 52, 53. The input element 51 consists, in this applicationto a clutch friction member, of a support disc 55 on each of the facesof which friction linings 56 are fixed, intended to be clamped betweenthe thrust and reaction plates of the clutch.

The friction lining support disc 55 is pressed against one of the guidewashers 52 of the main damper 50 whilst being fixed to it by the struts57.

The struts 57 pass through scallops 58 formed at the periphery of thedisc 54; the angular movement between the disc 54 and guide washers 52and 53 is limited through the cooperation of the struts 57 with the edgeof the scallops 58.

The guide washers 52 and 53 surround the output element 61 of thedamping device consisting of an internally fluted hub at 62; the sameapplies to the disc 54 of the main damper 50, which for its part mesheswith clearance with external flutes 63 on the hub 61 having a portion 64of reduced height at one of its ends.

The predamper 80 is located between the disc 54 and one of the guidewashers, here the washer 52, of the main damper 50, and this radiallybelow the springs 60 of the said main damper 50. The predamper 80 alsohas two guide washers 82, 83 disposed on each side of a disc 84 fixedwith respect to rotation to the portion 64 of the flutes 63 on the hub61. Circumferentially acting elastic members 85, here helical springs,elastically couple the guide washers 82, 83 to the disc 84. This disc 84of the predamper 80 is crimped to the hub 61.

The springs 85 of the predamper 80 are less stiff than the springs 80 ofthe main damper 50.

The predamper 80 is adapted to filter the vibrations notably in theidling range of the engine, whilst the main damper 50 is adapted tofilter the vibrations in the normal operating range of the vehicle,referred to as the running range. Each of the dampers 50, 80 has aspecific axially acting friction device 59, 86, in a manner known perse.

The springs 60 of the main damper are placed in windows placed oppositeeach other formed in the guide washers 52, 53 and in the disc 54. Inorder not to complicate the drawing, and to facilitate the explanation,these windows have been superimposed in the diagram in the diagram inFIG. 7. The windows 64, 65 are formed in the guide washers 52, 53, andthe window 66 in the disc 54. These windows have internal 74 andexternal 77 edges, and lateral edges 75 and 76 serving as an abutmentfor the springs 60; according to the invention, the external edge 77 ofthe windows 64, 65 formed in the guide washers 52, 53 has a portion Awhich is offset internally, that is to say radially towards the rotationaxis 90 of the input 51 and output 61 elements. This radial offset issuch that the portion A is as close as possible to the external contourof the spring 60; as will easily be understood, this portion A makes itpossible to limit considerably the deformation of the spring 60 underthe effect of centrifugal force; this portion A extendscircumferentially in an area 93 which is not swept by the end turns ofthe spring 60 during the relative movement of the input 51 and output 61elements, this being valid in one direction or the other, that is to sayin the driving direction where the engine of the vehicle drives thewheels thereof and which corresponds to a movement of the windows in thedisc in the clockwise direction about the axis 90, as seen in FIG. 7,with respect to the windows in the guide washers, as well as in theretro direction in which the wheels of the vehicle are driving withrespect to the vehicle engine, which corresponds to a movement of thewindows in the disc in the reverse direction compared with the previousone; in the above two cases, the angular movements are not equal, themovement being greater in the first case: consequently, as shown in FIG.7, the portion A is offset circumferentially in the direction whichcorresponds to the direction of rotation of the vehicle engine.

The invention also makes provision for connecting the external edge 77to the lateral edges 75, 76 by means of the portions B and C in theshape of an arc of a circle whose centre is merged with the rotationaxis 90 of the input 51 and output 61 elements: by virtue of thisarrangement, the end turns will, in spite of the centrifugal effect,always remain maintained in the angle formed by the lateral edges 75, 76and the portions B and C, and, during the angular movement, the actionon the springs by the disc will always take place through the lateraledges of the windows in the disc, that is to say without parasiticfriction, the external edge of the windows in the disc being free withrespect to the portions B and C.

Naturally, the portions A on the one hand and B and C on the other handare separated by clearance portions D, D2, that is to say ones offsetradially towards the outside with respect to them.

In order to simplify the design, the internally offset portion A is inthe shape of an arc of a circle whose centre 100 is situated towards theoutside with respect to the axis 90; for the same reason, the clearanceportions D, D2 are also arcs of a circle belonging to the same circlewhich defines the internally offset portion A.

Connecting portions E, of roughly radial orientation, connect theinternally offset portion A to each of the clearance portions D and D2.

Naturally, in all the above, the circumferentially acting elastic meanscan consist, in each group of windows, of a single helical spring, ortwo concentric helical springs, as shown in FIG. 6.

What is claimed is:
 1. Torsion damper disposed between two rotatingelements, an input element (51) and an output element (61), and havingcircumferentially acting elastic members (60), two guide washers (52,53) associated with one (51) of the elements and disposed axially oneach side of a disc (54) associated with the other one (61) of theelements, the circumferentially acting elastic members (60) having anaxis (70) and acting between the two guide washers (52, 53) and the disc(54) whilst being placed in windows (64, 65, 66) placed opposite eachother and formed in the guide washers (52, 53) and in the disc (54),said windows (64, 65, 66) having two lateral edges (75, 76) on which theends of the elastic members (60) are adapted to be in abutment, thewindows (64, 65, 66) having an external edge (77), the external edge(77) of the windows formed in one of the guide washers (52, 53) have aportion (A) offset internally, that is radially towards the rotationaxis (90) of the input (51) and output (61) elements, in an area (93)which is not swept by the ends of the elastic members (60) during therelative rotational movement, in one direction or the other, of theinput (51) and output (61) elements, wherein the windows (64, 65) in thetwo guide washers (52, 53) having said external edge (77) which definessaid internally offset portion (A), which extends circumferentially inthe shape of an arc of a circle whose center (100) is situated between arespective one of said windows (64, 65) and the rotation axis (90) ofthe input (51) and output (61) elements.
 2. Damper according to claim 1,characterised by the fact that the said external edge (77) is theexternal edge of the windows formed in the guide washers (52, 53). 3.Damper according to claim 1, characterised by the fact that the elasticmembers (60) are helical springs coiled about their axis (70).
 4. Damperaccording to claim 1, for a motor vehicle, characterised by the factthat the input element (51) is intended to be fixed or fixable to thevehicle engine flywheel, the output element (61) being intended to beconnected to the input of the vehicle gearbox.
 5. Torsion damperdisposed between two rotating elements, an input element (51) and anoutput element (61), and having circumferentially acting elastic members(60), two guide washers (52, 53) associated with one (51) of theelements and disposed axially on each side of a disc (54) associatedwith the other one (61) of the elements, the circumferentially actingelastic members (60) having an axis (70) and acting between the twoguide washers (52, 53) and the disc (54) whilst being placed in windows(64, 65, 66) placed opposite each other and formed in the guide washers(52, 53) and in the disc (54), the said windows (64, 65, 66) having twolateral edges (75, 76) on which the ends of the elastic members (60) areadapted to be in abutment, the windows (64, 65, 66) having an externaledge (77), the external edge (77) of the windows formed in one of theguide washers (52, 53) have a portion (A) offset internally, that isradially towards the rotation axis (90) of the input (51) and output(61) elements, in an area (93) which is not swept by the ends of theelastic members (60) during the relative rotational movement, in onedirection or the other, of the input (51) and output (61) elements,wherein the windows (64, 65) in the two guide washers (52, 53) have anexternal edge (77) which has an internally offset portion (A), whichextends circumferentially in the shape of an arc of a circle whosecenter (100) is situated towards the outside with respect to therotation axis (90) of the input (51) and output (61) elements, andwherein said external edge (77) is connected to the lateral edges (75,76) by portions (B, C) in the shape of an arc of a circle centered onthe rotation axis (90) of the input (51) and output (61) elements. 6.Damper according to claim 5, characterised by the fact that, between theinternally offset portion (A) on the one hand and each of the connectingportions (B, C) on the other hand, the external edge (77) has clearanceportions (D, D2) offset radially towards the outside.
 7. Damperaccording to claim 6, characterised by the fact that the clearanceportions (D, D2) are arcs of a circle belonging to the same circle whichdefines the internally offset portion (A).
 8. Torsion damper disposedbetween two rotating elements, an input element (51) and an outputelement (61), and having circumferentially acting elastic members (60),two guide washers (52, 53) associated with one (51) of the elements anddisposed axially on each side of a disc (54) associated with the otherone (61) of the elements, the circumferentially acting elastic members(60) having an axis (70) and acting between the two guide washers (52,53) and the disc (54) whilst being placed in windows (64, 65, 66) placedopposite each other and formed in the guide washers (52, 53) and in thedisc (54), said windows (64, 65, 66) having two lateral edges (75, 76)on which the ends of the elastic members (60) are adapted to be inabutment, the windows (64, 65, 66) having an external edge (77), theexternal edge (77) of the windows formed in one of the guide washers(52, 53) have a portion (A) offset internally, that is radially towardsthe rotation axis (90) of the input (51) and output (61) elements, in anarea (93) which is not swept by the ends of the elastic members (60)during the relative rotational movement, in one direction or the other,of the input (51) and output (61) elements, wherein the windows (64, 65)in the two guide washers (52, 53) having said external edge (77) whichdefines said internally offset portion (A), which extendscircumferentially in the shape of an arc of a circle whose center (100)is situated towards the outside with respect to the rotation axis (90)of the input (51) and output (61) elements and wherein said internallyoffset portion (A) is offset circumferentially in a directioncorresponding to a rotational direction of a vehicle engine adapted todrive said input member (51).